Dishwasher appliances generally include a tub that defines a wash chamber. Rack assemblies can be mounted within the wash chamber of the tub for receipt of articles for washing. Wash fluid (e.g., various combinations of water and detergent along with optional additives) may be introduced into the tub where it collects in a sump space at the bottom of the wash chamber. During wash and rinse cycles, a pump may be used to circulate wash fluid to spray assemblies within the wash chamber that can apply or direct wash fluid towards articles disposed within the rack assemblies in order to clean such articles. During a drain cycle, a drain pump may periodically discharge soiled wash fluid that collects in the sump space and the process may be repeated.
As part of a normal drain cycle, the dishwasher uses the drain pump to discharge soiled wash fluid through a drain hose to an external drain. Notably, the external drain is typically located above the drain pump. To prevent the soiled wash fluid from flowing back into the sump of the dishwasher, conventional drain system designs position a check valve on the drain hose, e.g., downstream of the drain pump, to prevent wash fluid in the drain hose from reentering the drain pump or sump.
Notably, such a configuration results in several disadvantages. For example, the volume of soiled wash fluid that remains in the drain pump upstream of the check valve could reenter the sump and be recirculated onto the dishes during a subsequent wash cycle. In addition, to resolve drain clog issues, the check valve would need to be accessed by removing the dishwasher from the cabinet. Notably, such a procedure is time consuming and costly. In addition, because the conventional check valve prevents wash fluid from remaining in a drain volute of the drain pump, the pump may become “air locked” and require priming before effective pumping may be achieved during the next drain cycle. This priming procedure typically involves pulsing the drain pump on and off to remove air from the drain volute, which degrades sound quality and the user experience in general.
Accordingly, a dishwasher appliance that utilizes an improved check valve assembly would be useful. More specifically, a check valve assembly that prevents the backflow of soiled wash fluid, simplifies the process for removing clogs, and improves the general operation of the dishwasher appliance would be particularly beneficial.